1. Technical Field
The present invention relates to a travelator for conveying passengers. More particularly, the invention relates to a belt pulley for use in such a travelator.
2. Related Art
The following patent documents disclose travelators intended for transporting people: Japanese patent document JP 2003-20181, U.S. Pat. No. 1,689,201, U.S. Pat. No. 2,769,522 and U.S. Pat. No. 3,592,139. In these patent documents, the conveyor includes a large number of adjacent narrow belt loops, several such belt loops being arranged over the width of the conveyor to transport users of the travelator. The conveyor has a large number of shafts mounted with bearings on the conveyor frame and arranged to be parallel to each other, at a distance from each other and transverse to the transport direction of the conveyor. Coupled to each shaft are a number of belt pulleys placed side by side.
Further, the conveyor comprises a number of mutually parallel endless belt loops, which form the moving conveying surface of the conveyor. The mutual arrangement of the belt loops is so implemented that they are interlaced with respect to each other in a comb-like fashion around each shaft. Each belt loop is passed over two belt pulleys on two successive shafts. Of each two closely adjacent belt loops on the same common shaft that are passed over adjacent belt pulleys, one belt loop is passed over a belt pulley on the previous shaft adjacent to the common shaft while the other belt loop adjacent to the aforesaid belt loop is passed over a belt pulley on the next shaft adjacent to the aforesaid common shaft.
The belts have a width of e.g. about 5 to 8 mm, preferably 6 mm, and thus, if the travelator has a width of e.g. 1 m, the number of parallel belt pulleys arranged on one shaft is large, e.g., 100 to 200 pulleys. Producing such a belt pulley combination, especially as a single component, can be very difficult even in a case where the belt pulleys on the same shaft are identical to each other and have the same diameters/numbers of teeth. It can be more difficult to produce a combination of a shaft and a set of belt pulleys with adjacent belt pulleys having different diameters/numbers of teeth in a manner advantageous with respect to economy and manufacturing technology. Pulley combinations of the afore-mentioned type are sometimes needed in high-speed travelators designed to achieve a transport speed (on the order of 5 m/s) substantially higher than the conventional transport speed (0.6 to 0.8 m/s). Therefore an acceleration section, a constant speed section, and a deceleration section are often required. In the acceleration and deceleration sections, adjacent toothed belt pulleys on the same shaft have different diameters/numbers of teeth. A further problem sometimes encountered with traditional solutions is poor dimensional accuracy and poor strength.